The present invention relates to novel synbiotic products comprising a combination of spore-forming probiotic bacteria with prebiotic compounds capable of providing nutrients to the probiotic bacteria and/or capable of encouraging the growth of resident beneficial bacteria, such as Lactobacillus or Bifidobacterium, present in the gastro-intestinal tract. Such synbiotic product compositions may enhance the health benefits of food products containing such synbiotic compositions.
There is increasing demand for functional food ingredients, both for human and animal consumption, that deliver health benefits in addition to nutrition. One class of such health-related food ingredients are known as “prebiotic” compounds. Representative examples of prebiotic compounds that are currently used in food products include a wide variety of carbohydrates, such as various sugars and starches. Many carbohydrates that have caloric value are digested to monosaccharides or short-chain oligosaccharides in the human upper gastro-intestinal tract (e.g., the mouth, the stomach, and the small intestine) and are readily absorbed into the blood stream. In addition to such readily metabolized carbohydrates, some carbohydrates act as dietary “fiber” in food products. Fiber compounds are generally not broken down, or only partially digested, in the upper gastro-intestinal tract and substantial amounts pass into the colon relatively intact. The benefits of fiber to human health are well established and recognized by nutrition scientists worldwide, such as, for example, in US government dietary recommendations. Studies have suggested that diets rich in dietary fiber can reduce the risk of cardiovascular disease, cancer, gastrointestinal problems, and obesity. See Campos et al., Nutr Hosp. 2005 January-February; 20(1):18-25 (suggesting a link between the occurrence of colorectal cancer and low fiber diet); Kendall et al., Curr Atheroscler Rep. 2004 November; 6(6):492-8 (suggesting that a diet rich in fiber can reduce LDL cholesterol); Kendall et al., J AOAC Int. 2004 May-June; 87(3):769-74 (suggesting that a diet high in fiber can reduce the risk of chronic disease); Cernea et al., Acta Diabetol. 2003 40 suppl 2:S389-400 (suggesting that a diet high in fiber can reduce the risk of cardiovascular disease).
There is increasing evidence that many of the health-promoting effects of dietary fiber are due to fermentation of these carbohydrates by a complex consortia of microorganisms (the microbiota) in the large intestine (Gibson, Glenn, “Dietary modulation of the human gut microflora using prebiotics,” Journal Of Nutrition, 80(2):S209-S212 (1998)). A sub-class of carbohydrate fibers, “prebiotic” carbohydrate compounds, have been reported to be especially beneficial in promoting and maintaining health in normal humans. Representative examples of dietary fiber carbohydrates with established prebiotic activity are inulin and fructo-oligosaccharides (Roberfroid, et al., “The Bifidogenic Nature of Chicory Inulin and Its Hydrolysis Products,” Journal of Nutrition, 128, 1, 11-19, 1998. Gibson, “Dietary Modulation of the Human Gut Microflora Using the Prebiotics Oligofructose and Inulin,” Journal of Nutrition, 129, 7 Suppl., 1438S-1441S, 1999); lactulose (Tuohy, et al., “A human volunteer study to determine the prebiotic effect of lactulose on human colonic microbiota,” Micro. Ecol. Health Disease 14, 165-173 (2002)); and soluble corn fiber (SCF) (U.S. patent application Ser. No. 12/124,364).
In addition to “prebiotic” ingredients, there is a growing market for foodstuffs and animal feeds that are formulated with “probiotic” bacteria. For example, there is increasing interest in the use of probiotic organisms as feed additives for animals, primarily as possible replacements for antibiotics. Many bacteria that are considered to have beneficial probiotic properties are normal commensal bacteria present in the healthy human or animal gut microflora. The most frequently used human probiotics include the Lactobacilli and Bifidobacteria. However, use of either of these bacterial groups as probiotic food or feed additives is fraught with difficulties. In order to be of benefit, the bacteria must survive the manufacturing process as viable cells, and be formulated as stable products (i.e., no significant loss of viability on storage for long periods and sometimes under adverse conditions). In addition, the bacteria must survive passage through the extreme acidity of the stomach and exposure to bile salts in the upper small intestine. It is hypothesized that the beneficial effects of probiotics are due to brief colonization of the small intestine and/or the colon which entails successfully competing with the existing microbiota that number some 107 to 1011 living bacteria per gram of luminal contents.
Several types of spore-forming Bacillus are currently sold as probiotics for both human and animal applications. For example, it has been reported that B. subtilis is sold over-the-counter for a variety of intestinal problems (Casula and Cutting (2002), Applied Environmental Microbiology, May 2002, pp. 2344-2352; Green, DH, et al. (1999) Appl. Env. Microbiol. 65, pp. 4288-4291) and for the treatment of diarrhea (Mazza, P (1994) Boll. Chim. Farm. 133, pp. 3-18). Studies of commercial preparations of B. clausii have also been reported, for example, by Marseglia, et al. (2007), and Canani, et al. (2007). Marseglia, GL, et al. (1997) Ther. Clin. Risk Manag. 3, pp. 13-17; Canani, RB, et al. (2007) BMJ, August 18, 335(7615): 340.
One of the probiotic strains with the longest history of human use is Bacillus coagulans, which was first described in the 1930's as Lactobacillus sporogenes ((Devechihi, E. and Drago, L. (2006) Int. J. Probiotics Prebiotics 1, pp. 3-10)). This strain(s) is of particular interest as it is one of the few studied spore-forming strains that produce large amounts of lactic acid from sugars without the production of gas. B. coagulans probiotic strains are reported to produce terminal spores and the vegetative cells are facultative anaerobes and motile (Devechihi and Drago, 2006).
Duc et al. evaluated five commercial products that consisted of strains of Bacillus spores. Three strains of B. cereus were shown to persist in the gastro-intestinal tracts of mice for 18 days, which was taken as evidence of colonization (Duc, L H, et al. (2004) Appl. Environ. Microbiol. 70, pp. 2161-2171). Leser et al. describe the feeding of B. subtilis and B. licheniforms spores to pigs (Leser, TD, et al. (2008) J. Appl. Microbiol. 104, pp. 1025-1033). Within two weeks of the start of feeding these probiotics, spores were found in all regions of the pig gastrointestinal tract. It was estimated that 70-90% of the spores germinated and there was limited and transient vegetative growth in the gastro-intestinal tract.